1. Field of the Invention
The present invention relates to a liquid crystal display (LCD) device, and more particularly to a liquid crystal display device using a radiation-cured sealant.
2. Description of the Related Art
Liquid crystal displays typically comprise two oppositely positioned first and second substrates and a liquid crystal layer interposed therebetween. In the field of flat panel displays, the two substrates may be affixed to each other with a thermosetting epoxy. However, this method takes considerable processing time for completion of liquid crystal injection.
Recently, U.S. Pat. No. 5,263,888 discloses a one drop fill (ODF) method comprising the steps of applying an adhesive onto the entire periphery of the first substrate, dropping the liquid crystal material to the first substrate, superposing the second substrate upon the first substrate and pressing the substrates until a gap between the substrates reaches a predetermined value (typically 3-10 micrometers), and curing the adhesive. In the step of pressing the substrates, the liquid crystal material spreads to fill the space between the substrates thereby forming the liquid crystal layer under a preferably controlled cell gap. This method significantly shortens the process time and increases the manufacturing efficiency. However, this one-drop fill method cannot use the thermosetting epoxy but must use instead a UV curable sealant which cures near room temperature.
FIG. 10 shows a portion of a conventional liquid crystal display device 900. As shown in FIG. 10, the liquid crystal display device 900 mainly includes a first substrate 902 and a second substrate 904 disposed to face each other with a predetermined gap therebetween. A liquid crystal layer 906 is sandwiched between the substrates 902 and 904. The substrates 902 and 904 are affixed to each other by a sealant 907. Specifically, the first substrate 902 is provided with a plurality of colored patterns 918 (only one is shown in FIG. 10), a counter electrode (not shown) and a black matrix 922. The second substrate 904 is provided with a plurality of addressing lines 908 and pixel electrodes 916. The black matrix 922 is typically made of a light-blocking material to deter external light from entering the display device. As shown in FIG. 10, when a UV curable sealant is used to seal the liquid crystal display device 900, it is necessary to have the sealant 907 provided in the periphery of the black matrix 922 to allow sufficient light to enter the liquid crystal display device from the substrate 902 to reach the sealant 907. However, the wide dispensing area of the sealant may undesirably increase the panel size and reduce the space for other circuit design. The present invention therefore seeks to provide a liquid crystal display device that overcomes or at least reduces the above-mentioned problems of the prior art.